Spinning mules



Dec. 6, 1955 N. H. CHAMBERLAIN ET AL SPINNING MULES 4 Sheets-Sheet l Filed April 10 Dec. 6, 1955 N H, CHAMBERLA|N ETAL 2,725,709

SPINNING MULES Filed April 10, 1953 4 Sheets-Sheet 2 Dec. 6, 1955 N. H, HAMBERLAIN ET AL 2,725,709

SPINNING MULES 4 Sheets-Sheet 3 Filed April 10, 1955 6, 1955 N. cHAMBERLAN ET AL 2,725,709

SPINNING MULES Filed April 10, 1953 4 Sheets-Sheet 4 Sia/L W End .gom

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United States Patent O PlNNNG M ULES Norman Henry Chamberlain, Leeds, and Brian Edmund King, Prestwich, England, assignors to T. M. M. (Research) Limited, Gldham, England, a British company Application April lil, 1953, Serial No. 348,@74

Clains priority, application Great Britain April 16, 1952 Claims. (Cl. 57-41) In some types of spinning mule all, or the greater part of, the draft is eftected by movement of the carriage in relation to the delivery rollers. It is general practice, in woollen spinning mules for example, to cause the carriage to move out at constant speed until the delivery rollers stop and then to decelerate the carriage uniformly during the remainder of its outward run, i. e. during the actual drafting of the slubbing, the speed of the carriage being reduced to zero at the extreme end of the run. The spindles rotate at constant speed during the whole of the outward run of the carriage' At the point in the outward run of the carriage at which the delivery rollers stop and drafting commences, the twist in the yarn', measured in turns per inch, is considerably lower than the drafting twist, i. e. the twist in the yam at the end of the outward run. As drafting proceeds, however, the twist in the yarn increases due to the combined efiect of the deceleration of the carriage and the constant spindle speed.

The deceleration of the carriage during the draftng period however lengthens the time occupied by the outward draw and so reduces the production of the mule.

Atternpts have been made to depart from this conventional method of drafting and twisting during the outward run of the carriage by driving the delivery rolle's throughout the outward run of the carriage so that they deliver slubbing at a substantially constant rate whilethe carriage moves out at a faster rate for the greater part of the outward run, With the result that drafting takes place throughout substantially the whole of the outward run. No attempt, however, was made to increase thespindle speed as drafting proceeded, and we believe that for this reason this method of drafting was never completely successful.

The invention provides a method of Operating a spinning mule which comprises movng the carriage at a substantially constant speed throughout the major portion of its outward run and progressively increasing the spindle speed during the portion of the outward run in which drafting is taking place. By referring to the "major portion of the outward run, we means that the carriage speed is substantially constant throughout the whole of the outward run, subject only to a short acceleration period at the start of the run and, if found desirable, a short deceleration period at the end of the run to avoid bumping of the carriage.

In its preferred form, the method according to the invention comprises driving the delivery roller-s during the initial part of the outward run to deliverslubbing at the same rate as that at which the carriage is travelling, stopping them at an intermediate point in the outward run, driving the spindles at substantially constant speed while the delivery rollers are running and thereafter progressively increasing the spindle speed until the end of the outward run.

The conjoint effect of constant, or substantially constant, carriage speed during substantially the whole of the drafting period and increasing spindle speed results,` as

in the case of the conventonal practice referred to above, in a rogressive increase in the twist in the ,yarn during the drafting period. The method according to the invention, however, involves two advantages over this existing practice. Firstly, the time required for the carriage to reach the end of its outward run is substantially shortened. This shortening may amount to as much as onethird of the total time required for the outward run for drafts of the order of 2 and aifords a valuable increase in production. Secondly, the spindles will be rotating at a fairly fast speed at'the end of the outward run, and the time required to bring them up to full twisting speed will accordingly be reduced.

The method according to the invention may, however, also be applied to the above-mentioned alternative system of drafting and twistng by driving the delivery rollers, for example through change-speed gearing, so that they deliver slubbing throughout the outward run of the carriage at a predetermined rate which is slower than.

the rate of outward travel of the 'carriage and progressively increasing the spindle speed throughout the outward run. In this case also the carriage may, if desired, be subjected to a rapid deceleration at the end of its outward run. i

With this alternative method the conjoint eect of constant, or substantially constant, carriage speed and progressive increase in spindle speed throughout the outward run again results in a progressive increase in the twist in the yarn and the above-mentioned two advantages are again obtained. V

The invention includes a spinning mule comprising mechanism for driving the carriage at substantially constant speed throughout the major portion of its outward run, means for driving the delivery rollers duringthe initial part of .the outward run to deliver slubbing at the same rate as that at which the carriage is travelling and then stopping them, and mechansm for driving the spindles at substantially constant speed while the delive'y rollers are running and, after the delivery rollers have stopped, progressively increasing the spindle speed until the end of the outward run.'

Reference has been made above to provsion for rapid deceleration of the carriage at the end of the outward run. This may not, however, be necessary as the carriage moves out at a comparatively slow speed, not normally exceeding about 18 inches per second, and Shock absorbers may, in appropriate cases, be used to absorb the bump at the end of the outward run.

In existing mechanical mules it is only possible to vary the spindle speed step-wise during the outward run, and while it is known to produce a step-wise increase in the spindle speed before the end of the outward run for the purpose of shortening the period required for'the insertion of the spinning twist, it has been the invariable practice to decelerate the carriage during the drafting period.

The invention, which is applicable to waste mules as well as to mules for spinning wool, may be applied to a mechanical mule by elimnating the scrolls, thereby giving a constant carriage speed on'the outward run, and driving the spindles from an electrc motor on the carrage, the motor being of a variable speed, mechanically controlled type, e. g. a motor with a brush-shifting speed control operated by a cam, to achieve the required control over the spindle speed. r

The invention can also be applied with advantage to mules of the kind described in United States patent application Serial No. 332,294, and one embodirnent of mule of this charactersembodying the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which-z Fig. 1 is a diagrammatic side elevation of the mule,

2 is *a diagrammatic plan view, on a larger scale, of the mechanism for driving thecarriage,

Fig. 3 is a diagramrnatic perspective view of the mechanism for driving the spindles,

-Fg. 4-is azpe'rspectiveviewof.the control drum andce taiu associated ,mecha'nisrm Fig. 5-is a circuit;diagram showingthe spindle and carriage speed voltageshaping circuits forsthezcarr'iag'e .outward run,

Figs. 6A and'B aretgraphs showing the rel'ationship of carriage and spindle ;speed during the .carriage outward run, and v Fig. 7 is asection through oreof the 'slipz-coup'lings.

Like 'reference: charactersdesignate like partsthroughout the figures, which illtstr-ate only thos'eportions of' the mule which are :essential ;to the 'understanding of the invention.

The mule .comprisesa carriagerztl (Fig. '1) supporting a tin roller 21, from 'whichthespindles 22 are'driven by the usual bands'not shown. The carriageis driven by an electric motor 23 mounted on the-machine framework through the-agency of an electro-magnetic slip'coupling 24 (Fg. 2) of known-type,to the field coiljofwhich'suitable excitation volta'gesare applied as later described.

As shown in Fig. 7-the couplingzcomprisesan armaturedrum 424 driven by the motor shaft'425 and a rotor 426 mounted on an output shaftl and carrying a coil 204. The ends of the coil 294 are connected 'by conductors (not shown) to sliprings '438 to which the eXcitation voltages are applied by meansof brushes429. When no current is passing'through the coi1 204, thedrum'424 rotates without impartingmovementto theoutput shaft 25. On application of a D. C. excitation voltage to the coil 204, however, an electro-magnetic drag is created between the drum 424-`and the rotor 426, causing the output shaft 25 to rotate -at a speed determined by the magnitude 'of said excit-ation voltage.

On the driven shaft 25 of-the coupling 24 are mounted an A. C. generator 26 excited by-a 'permanent magnet, and a pulley 27, which drives a c'lutch shaft 28 through a chain drive 29a. Fast on the shaft 28 is a clutch sleeve 29 and loose on the shaft 28 are a pair 'ot'clutch sleeves 30, 31 carrying gear wheels 32, 33 respectively.

The clutchsleeve 29 is controlledas -toposition bya lever 34, pivoted at 35 and :carrying an armature 36, cooperating -with apairof solenoids sol 1 and sol 2, which are alternatively energised, as described in United States patent application Serial No. 332,294, to cause one or other of the gear wheels' 32.33 to be driven by the shaft 28. When, as shown intFig. 2, 'the clutch sleeves 29, 30 are engagecha back shaft 37 is directly driven from the clutch shaft 28 through theagency of'a gear wheel 38 meshing with the gear wheel 32. When the clutch sleeve 29 is moved to its alternative position, which is that appropriate for the outward run of the carriage,'to'-engage the clutch sleeve 31, the backshaft 37 is driven in the reverse direction through the agency -of a'countershaft 39, carrying gear wheels 40, l-meshing respectivelywith the gear wheels 33, 38.

The back shaft 37 carries a sprocket t z (Fig. 1) engaging `a chain 43, which s-attached at its opposite ends to the carriage Zt) and passes around a'sprocket 44 mounted on the machineframe.

The material to bespun is w'oun'd on bobbins 45, -one of which 'is indica'te'd in Fig..`1, which are friction driven in the usual way from bobbin drive drums 46, the material passing between delivery rolle'rs 47 on its Way from the bobbins to the spindles. The drive to the delivery rollers is taken from the back shaft 37 through a chain drive 48 (Fig. 2), gear wheels 49, 50 and a ditferential'gear`5ll to the shaft 52 carrying the lower delivery rollers. The upper delivery rollers aredriven by frictional contact'with the lower rollers 'and the-drums 46 aredrivenfrorn the shaft 52by geafing't'hfishown) in the usualvay. The dfierential gear 51 comprisesa'par'of sun wlels'53,'54,

fixed respectively to the gear wheel and to the shaft 5,2.and p1anet wheels mounted on a carrier 56 formed with peripheral ratchet teeth 57. A pawl 53 is normally held by a spring 59 clear of the ratchet teeth 57, and no drive is then transmitted to the shat 52. When, however, a solenoid sol 3 is energised, under control of a switch operated by the carriage at the end of its inward run as described in. United States patent application Serial No. 332,294, the pawl 58 is moved to engage the `ratchet teeth`57, thereby locking the planet carrier 56 so that the 'chain drive 48 is then effective to drive the shaft 52 and therefore the delivery rollers. The drive of the delivery rollers -is terminated by engagement by the carriage of another switch which causes the solenoid sol 3 to be de energised lkewise a s described in 'United States patent application Serial No. 332,294.

The tin roller 21 (Pg. 3) is driven from an electric motor 60 on the carriage, through the agency of an electro-rnagnetic` slip` coupling *61, identical with the couplng shown "in "Fig 7, and achain drive'62. The output shatt-of the coupling-l drives an A. C. generator 63 precisely'similar to thegenerator 26 (Fig. 1), Appropriate excitaton voltages are applied to the coupling 61, as later described, to'cause the spindles't o'be driven atthe appropriate speeds as requiredduring theoutward runof the carriage.

The'mule embodes `'a tnain `relay system, fully' described in 'United States patent application Serial No. 332,294,

Jhich Controls switch contacts Az, fis, '1 3, G3, Hz, D2, J2, 1 2, -G2 (Fig. 5 so *as 'to apply at 'the appropriate times in the -rnachine cycle various `voltage 'shaping circuits to the grids of 'a "pair'o'f 'cathode 'follower valves 136, 137. Fig. 5 shows the'voltage shaping circuits which are applied to the carriage and's'pindles'during the outward run of the carriage, and reference should be made to United States-patent application Serial'No. 332294 for a description of the others. The output of the valve 13 6 determines the-excitation of the cou'plin'g 24 for driving the carriage and the output ofthe valve 137 deternines the excitation of the coupling 61 'for driving the spindles also as fully described in United 'States'patent application Serial No. 332,294. lt Will-besuflicient here to say that the higher the voltage appliel'to 'the *gridof the valve '136 or 137, the lower willbe the 'speed of the carriage orspindles as the-`case maybe.

The main relay system is controlled, as described in United States patent application Serial No. 332294 jointly by'certain carriage-operated switches and by contats DCl-DCS ``(-Fig l-*operatecl by'pins 77'on a rotary control drum 'drivehbyamotor 7%'. This control drum carries a toothed segm'ent78. The segment'' is eFective, during a certain portion of thecycle of rotation 'of the control r ytorotat pi i s rea, The 'pinion is coupledto the sliderlfFigLS') -o'f an adjustabl'e rheostat 315 and fulfills a'tunction described later.

Fig. 6A illustrat'es *typical spindie 'and carriage speed curves obtaiued with afnormal woollen mnie or witha mule as described i'n "United States patent application Serial No. 332,2*94,'and'it will'be seen that the carriage is rapidly-accelerated at the c'ornnencement of the outward run, and then remains'at a constantspeedthroughout the period When *thedelivry 'rollers "are delivering slubbing. At the drafting' point A'(which varies in position according to the draft required) thetdelivery rollers are stopped and the carriage'decelerates 'throughout the ensuing drafting period until, at the'en'cl of 'the outward run, the speed is close to zero. The's'pindles accelerate qui 15-/ at the commencement'of the outward run and remain at a constant speed until the carriage reaches the end of the outward run.

Fig, '6B illustrates 'typical spindle and Carriage speed curves when using the new method of ,operation according to the invention. Theicarriage and spindle speeds during-thegpart of the outward run of .the carriage prior to teaching the point A are similar to 'those shown in Fig. 6A but, when drafting commences at point A, as the result of stoppage of the delivery rollers by de-energisation of the solenod sol 3, the carriage speed remains constant until the end of the outward run except for rapid deceleration close to the end of the run to bring the carriage to rest. The spindle speed increases from the point A to ensure that sufficient twist is inserted in the yam to enable it to withstand the higher rate of drafting without breaking.

The spindle and carriage speed curves shown in Fig. 6B are obtained by the voltage shaping circuits shown in Fig. 5 as will now be described.

The carriage voltage shaping crcuit for the outward run Will first be described. At the start of the outward run, the switch contact J is lifted, by the main relay system, to its upper contact as described in United States patent application Serial No. 332,294. A crcuit is then established from the grid of valve 136 by Fs upper contact, 13 upper contact, A2 lower contact, C/ S7 upper contact via the ofr position of a slow start selector switch 299 and resistance 302 to earth. The control voltage applied to the coupling excitation unit consists of the voltage across the lower portion of a resistor 302 in the potentiometer chain 300, 301, 302. This voltage, therefore, determines the velocity with which the carriage commences its outward nm, and the adjustable slider of resistor 302 therefore constitutes the Initial Speed control for the carriage.

It is sometimes desirable that the carriage shall move away from rest on the outward run with an acceleration less than that given by the crcuit just described. To ef- A fect this, the switch 299 is used to introduce a condenserresistance delay into the voltage shaping crcuit for the outward carriage run. Immediately prior to the commencement of the outward run of the cariage, switch contact Ja is on its lower contact, stop excitation is applied' to the grid of the valve 136 from the connection between resistors 162 and 163 in the potentiometer chain 162, 163, 164, and a condenser 298 is charged to the stop excitation voltage. In the off position of the switch 299, the condenser 293 is at once discharged, as soon as Ja moves to its upper contact, through the relatively small resistance of the lower part of resistor 302. When, however, the switch 299 is moved to any of its terminals 1, 2, 3, resistors 303, 304- and 305 of different values are connected in series with the carriage run out voltage shaping crcuit. The run out excitation to the carriage coupling cannot then build up faster than the condenser 298 can' discharge i through the resistor 303, 304 or 305 in the voltage shaping crcuit and acceleration of the carriage is correspondingly delayed, giving a slow start.

When the condenser 298 has discharged to a potential equal to that at the slider of resistor 302, the carriage continues the run out at constant speed until it moves to its lower contact the carriage-actuated switch C/S7, which is situated close to the end of the outward run. Immediately prior to movement otswitch C/S7 to its lower contact, a condenser 308 has been charged to the difference in potential between the point 307b and a point 307a in the resistance chain 306, `307. The voltage -at the point 3070 corresponds to a crawler speed of the carriage and on operation of the switch C/S7 the condenser 308 is discharged through a resistor 309 and the voltage at the grid of 136 will increase, at a rate dependent on the discharging time of the resistance-capacity crcuit 309, 303, until it reaches that' of the point 307a. The 'carriage speed theretore decreases, as determined by the crcuit 308, 309, until it reaches the crawler speed. This will occur just before the carriage reaches the end of the outward run. The rate of deceleration of the carriage can be varied over a given range by adjustment of the variable resistance 309. The rate of deceleration will be atfected by the condenser 298, the actual value of the time constant depending on the parallel combination'of condensers 298 and 308 with a selected part of the resistance 309.

The voltage shaping circuits for the spindles during the carrage outward run will now be described. At the start of the outward run, J2 moves to its upper contact to establish a crcuit from the grid of valve 137 via Fz upper contact, J2 upper contact, D2 lower contact, and resistances 322, 324, 323 to earth. The voltage applied to the grid of 137 will be the algebraic sum of all D. C. voltages in this crcuit and therefore, when the slider 314 is resting at its zero position, as shown, and no voltage is applied to the grid of an amplifier valve 316, it will consist only of the voltage across the lower portion of resistance 324 and resistance 323. This voltage, therefore, determines the speed of the spindles as the carriage commences the outward run, and slider 321 is the Initial Speed" control for the spindles.

The crcuit for producing the spindle acceleration shaping voltage operates in the following manner.

The numeral 310 is a triode connected as a conventonal cathode-coupled Hartley oscillator, and serves as a local oscillator generating an A. C. voltage at approximately 1500 cycles per sec. The output from the cathode of valve 310 is coupled direct to the grid of 311, a second triode functioning as a cathode follower butter stage isolating the oscillator from the grid crcuit of the valve 316. Part of the oscillator output is taken from the cathode load of valve 311 and applied via condenser 312 across the rheostat 315. The sector 78 (Fig. 4) is so positioned in relation to the control drum 69 that it engages the pinion 109 and begins to rotate the slider 314 (Fig. 5) away from its zero position at, or approximately at, the moment when the movement of the delivery rollers 47 is terminated by de-energisation of the solenod sol 3 (Fig. 2) as already described. Since the number of teeth on the sector 78 is exactly equal to the number of teeth on each of the pinions 109, 145, the slider 314 is rotated through exactly one revolution at each revolution of the drum and so returned to its original position ready for the next operation. As the slider314 is rotated by the sector 78, a gradually increasing voltage at 1500 cycles per sec. is applied to the grid of the amplifier valve 316. This voltage reaches a maximum as the slider 314 reaches the upper end of the rheostat 315 and returns rapidly to zero as it crosses the gap between the ends of the rheostat.

The A. C. voltage applied to the grid of' 316 by the slider 314 is amplified and stepped up by the anode transformer 317, so that approximately 400 volts are available across the secondary of 317. This secondary is connected in crcuit with a potentiometer 319.

A diode 320 rectifies the potential picked up by the slider 318 of the potentiometer and applies across the resistor 322 a D. C. potential determined by the position of the slider 318. As described earlier, the resistor 322 is connected in series with the spindles voltage shaping crcuit for the carrage outward run. As soon as the sector 78 picks up the slider 314 and commences to turn it, a voltage begins to appear across 322, and increases at a rate dependent on the setting of slider 318. This voltage is in the opposing sense to that already included in the above crcuit. Hence the voltage at the grid of valve 137 decreases as the slider 314 is turned. The spindle couping speed increases at a rate dependent on the rate of build up of the D. C. voltage across resistance 322, which is governed by the setting of slider 318. The latter, therefore, constitutes the Rate of Acceleration" control for the spindles. It should be noted that the adjustments of sliders 318 and 321 are quite independent. The initial speed can be varied at will without afiecting the rate of acceleration and vice versa; and since the point in the outward run of the carriage at which the spindle acceleration starts is determined by the point of which slider 314 begins to rotate, and this in turn is set by the position of the sector 78 in relation to the control drum 69, the onset of acceleration can also be varied without, aitecting, either the rate of acceleration or, the initial spindle speed.

Toprevent thegrid of valve 137 being drivennegative to earth potential, due to the large negative voltage set up at the upper end of resistance 322, a diode 327 is provided. Its ,cathode is connected to the point 330 and its anode is connected to the Slider 326 of a variable resistance 32@ in a potentiometer chain 328, 329. The diode 327 therefore prevents the voltage at the. grid of valye 137 from falling below that at the slider 326. A further eect of the diode 327 is to prevent the spindle speed during theontwardrun from ever rising above that during the high speed twisting period, which is also determined by the voltage picked otf by the Slider 326; This occurs by movement, of D2 to its upper contact at. the end, of the outward run# as described in United States application Serial No. 332,294.

What Weclaim as our invention and desire to secure by Letters Patent. is:

1. A spinning mule, comprisingacar-riage arranged to make alternate outward and inward runs, spindles, delivery rollers for supplying slubhing to the spindles, means for driving the delivery rollers during the initialportion of each outward run of the carriage and thereafter stopping them, so that the slubbing is drafted during the re,- maining portion of said outward run, mechanism for driving the carriage at substantially constant speed during the major portion of each outward run thereof a separate mechanism for driving the spindles,. and means controlling said spindle driving mechanism to drive said spindles at substantially constant speed during said initial portion of each outward run and toprogressively increase the spindle speed throughoutsaid remaining portion of each outward run.

2. A spinning mule, comprising a carriage arranged to make alternate outward andinward runs, spindles, delivery rollers for supplying slubbing to the spindles,tmeans for driving the delivery rollers during the initial portion of each outward run of the carriage and thereafter stopping them, so that the slubhing is drafted during the remaining portion of said outward run; mechanism for driving the carriage at substantially constant speed during the major portion of each ontward: run thereof, an electrically controllahle variahie speed driving mechanism for driving the spindles at a speed determined by an excitation voltage applied to said spindle drivng mechanism, a voltage shaping cireuit for applying, during said initial portion of eachoutwar-d run, a steady excitationvoltage to said spindle driving mechanism, and means for progressively varying an element of said circuit, throughout said remaining portion of each outward run to ettect a progressive increase inspindle speed.

3'. A spinning mule, compriing a earriage arranged to make alternate outward and inward runs, spindles, de-

llvery roller-s for supplying slubbing to the spindles, means for driving me delivery rollers during the initial portion of each outwarcl run of the carriage and thereafter stop ping them, so that the sluhhng is drafted during the re* maning portion of said outward run, mechanism for, driving the carriage at suhstantially constant speed during the major portion of each outward run thereof, an electrically controllable Variabie speed driving mechanismincluding a magnetc s ip coupling for driving the spindles, a voltage shaping circit for applying, during saidnitial portion of each outward run, a steady eXcitatio-n voltage to said slip coupling, and means for progressively varye ing an element of said circut, during said remaining portion of each outward ron, to effect a` progressive increase in spindle speed.

l'. A spinning mnie, comprising a carriage arranged to make alteri-rate outward and inward runs, spindles, delivery roiers for supplying slubbing to the spndles, means tor driving the delivery rollers during the nitial portion ofcach ontward run of the carriage and thereafte' stepping them, so that the slubbing is draftecl during? the remaining portion of said outwa'd run, mechanism for dri'ving the, carriage at sbstantially constant speed during the major portion of each o'tward run thereof, an electri'cally controllable variable speed driving mechanism for drit/ing the spindles, a voltage shaping circuit including a potentiometer for developng a steady voltage, and an adjustable resistor for modifying said voltage, means for applying to said drivingmechanisrn a voltage directly controlling the spindle speed' and inversely proportional totthe voltage developedby said voltage shaping circuit,

and means for actuating said adjustable resistor, during said remaining portion only of .each outward run, to reduce progressively the voltage developed by said voltage shaping ci'rcuit and thereby. to produce. a progressive increase in spindle speed.

5. A spinning mule according to claim 4, Wherein said voltage. shaping circuit comprises an oscillator for developing an A. C. voltage across the adjustabie resistor, a Slider for adjustng said resistor, a thermionic valve having a grid connected to said Slider, a series resistor in series with said potentiometer, and a rectier for rectifying the' output of said valve andarranged to apply across said series resistor a D. C. voltage determined by the position of said Slider and of opposite sense to the voltage developed' by said potentiometer.

6. A spinning mule according to claim 4, wherein said adjustable resi'stor includes a slider for adjusting it, and comprising a control drum, means for rotating said control drum in synchronism with the movements of the carriage, a toothed secto r on the control drum, and a vpinion connected to the Slider, said sector being arranged to engage said pinion to actuate said slder at the start of said remaining period of each outward run.

7; A spinning mule, cemprising a carriage arranged to make alternate o utward and inward runs, spindles, delivery roll'ers for supplying slubbing to the spindles, means for driving the delivery rollers during the initial portion of each outward run of the carriage and thereatter stopping them, so that the slubbing is drafted during the remaining portion of said outward run, an electrically controllable variabl'e speed driving mechanism for driving the carriage at each outward run, a voltage shaping circuit 'for' applying, dur-ing the major portion of each out- Ward run, a steady excitatio-n voltage to said driving mechanism, means for modifying said'excitation voltage, near the end of each outward run of the carriage, to provide rapid deceleration of the carriage, separate mechanism for driving the spindles, and mechanism for controlling said spindle driving mechanism to drive said spindles at substantially constant speed during said initial portion of each outward' run and to progressively in-' crease the spindle speed throughout said remaining portion of-=each outward run;

8; A spinningmule, comprising a carriage arranged to make alternate` outward and' inward runs, spindles, delivery rollers for supplying slubbing to the spindles, means for driving the delivery rollers during the initial portion of`eachoutWard run' of the carriage and thereafter stopping them, so that the slubbing is drafted during the' remaining portion of' said outward run, an electrically controllable variable speed driving mechanism including a magnetic slip coupling for driving the carriage at eachoutwardsrun, a-voltage shaping oircuit for applying, during the major'portion of each outward run, a steady excitation voltageto said' slip coupling, means for modifyingsaid excitation' voltage, near the end of each outward run of the carriage, to provide rapid deceleration of the carriage, and mechanism for driving the spindles at substantially constant speed during said initial portion of. each outward run and for progressively increasing the spindle speed during said remaining portion of each outward run.

9. A spinningmuleaccordingto claim 7, Wherein said voltags shaping circit includes a potentiometer, for proyidingvasteady excitation voltage during the major portion of each outward run, and a normally charged condenser, and wherein the means for modifying said excitation voltage comprises aswitch actuable by the carriage, near the end of the outward run, to connect the condenser in series with the voltage derived from the potentiometer and thereby to modify the excitation voltage so as to decelerate the carriage.

10. A spining nule comprising spindles, delivery rollers for supplying slubbing to said spindles, a carriage arranged to make outward runs, during which the slubbng is twisted to form a yarn and during part at least of which the slubbing is drafted, and inward runs, during which the yarn is wound on the spndles, mechanism for driving said carriage at substantially constant speed during the major portion of each outward run thereof, a separate driving mechanism for driving the spindles, and means for controlling said spindle driving mechanism to drive said spindles at progressively increasing speed during that portion only of each outward run in which drafting is taking place, said increase in the spirdle speed being limited to and extending throughout said drafting portion of the outward run.

References Cited in the file of this patent UNITED STATES PATENTS 617,048 Ramsden Jan. 3, 1899 1,255,934 Rundlett Feb. 12, 1918 FOREIGN PATENTS 296,756 Great Britain Sept. 19, 1929 447,309 Great Britain May 15, 1936 585,852 Great Britain Feb. 26, 1947 621,215 Great Britain Apr. 6, 1949 703,876 Germany Mar. 18, 1941 

